This is in response to your reasons for wanting to restart Touya... I don't think it's really necessary and, ultimately, I don't know if it'll really help you.
Characterization can be fixed without having to reset. If you look at any number of characters' intros, they're going to be a bit rocky. That's the point of an intro: it's how you get to know your character and settle into your voice. Usually there's going to be a rocky start and an adjustment period, unless you've played the character before already. Nobody is going to hold it against you if your intro or your first few entries are a little off. It's in the past.
Resetting won't be good for Touya just because he hasn't been involved for such a long time. Not only will it be an intro, which are already kind of boring (especially after a reset), but characters will also have to be all 'oh, you used to be here but you forgot' which will be awkward because he hasn't been involved for the longest time.
I think the best bet for you is to just ease yourself back into it. Plot stuff out with the Sakuras or the Syaorans. Reestablish old CR. Try out some event replays you haven't before. Touya has a lot of great CR and has had development (at least on the Syao front) and it'd be a shame to lose it all.
This will have the same purpose as a reset, only this time Touya will be interacting with people he at least is somewhat familiar with. The problem with a reset is that so many people don't know him and/or wouldn't care about the fact that he forgot. The most defining factor about him in-game is his relationship with Yuekito, which nobody really knew about because it was mostly in private between the three of them.
Not going with the reset means that he'll know a bit more about TRC, will have more reason to go :/ at Clow, have his CR with Hima and Gigei, for example. Rebuilding those things all over again can be trying for both sides and, ultimately, I don't think it will help your motivation for him.
When you play him, you play him well. People make mistakes with characterization all the time. Just put the past behind you and move forward and slowly ease yourself back into playing wit him. Resetting will only frustrate you, ultimately.
And on that note, I think that you need to ease yourself more into the game in general. You don't seem to be around all that much, aside from OTPs. I hardly see Keiichi around aside from talking with Kamui. I hardly see Takeshi around in longer threads outside of Ken or Hokuto. I think you'll be more satisfied and confident if you just branched out a bit, with all your characters.
Just don't be afraid to throw them places. Your characters are all fun, and when you play them they're fantastic.
I think you're especially too hard on yourself with Touya. If it's really so overwhelming, just start out with, say, threading with his sister. That's low-key and low-pressure because it's a canon-established CR.
So, tl;dr way to say that you shouldn't fret so much. Just play. The rest will follow from there.